Semiconductor Automatic Test Equipment (ATE) is widely used in the manufacturing industry to test the various types of semiconductor devices. Some examples are Integrated Circuit (IC) devices, printed circuit boards (PCBs), etc. A Device Under Test (DUT) is a term commonly used to refer to any device undergoing any testing. The DUT is usually inserted into a test socket that is connected to the ATE in semiconductor testing. There are a variety of test sockets available in the market today, such as Kelvin test sockets, multi-nest sockets and etc. As semiconductor devices continues to shrink in sizes and improving in its performance, manufacturing and testing these devices has become increasingly difficult.
A test socket provided with Kelvin contacts allows four-terminal measurements. Current test sockets with Kelvin contacts have tips that are angled to one side that is chamfered from a wire in order to test an IC small pad area. However, such Kelvin contacts have a small contact area with the DUT that affects the conductivity. The Kelvin contacts with tips angled to one side will also eventually wear off over continuous usage of the test sockets.
FIG. 1 is an exemplary illustration of a conventional contact tip 101 of a contact element 102 provided for a test socket 100. A wire is used to form the contact element 102 and its contact tip 101 is chamfered to a symmetrical sloping edge. The contact tip 101 is provided for testing of integrated circuit small pad area. However, the contact tip 101 with the symmetrical sloping edge is more susceptible to wearing off. As such, the contact tip 101 needs to be sharpened constantly to remain contactable with the integrated circuit small pad area. Additionally, the contact tip 101 of the contact element 102 has a small contact area. Further, the wire used to form the contact element 102 is made from different materials, width, or thickness to increase the contact element's overall spring force or hardiness.
US Patent document published as “U.S. Pat. No. 6,293,814” illustrates a cross-sectional view of a test socket 200 with Kelvin contact as shown in FIG. 2. The test socket 200 includes a pair of metallic electrodes with a flat contact edge tip 201 embedded in a non-conducting base 202. Each pair of metallic electrodes comprises a first metallic electrode 203 and a second metallic electrode 204. The first metallic electrode 203 and the second metallic electrode 204 are both embedded in the base. The pair of metallic electrodes is arranged mirroring each other in the non-conducting base 202. The first metallic electrode 203 is for contact with a lead of an Integrated Circuit (IC) device 205. Each electrode is electrically insulated from each other. During the testing of the IC device 205, a slight pressure when the IC device 205 is placed onto the test socket, presses the first metallic electrode 203 downwards to come into effective contact is contactable with the second metallic electrode 204.
US patent document published as “U.S. Pat. No. 7,256,598” discloses a hybrid non-abrasive electrical test contact element 301 of another test socket 300 as shown in FIG. 3. The contact element 301 is able to contact a lead of an integrated circuit device under test without abrading the plating on the lead. The contact element 301 possesses multiple loops to allow the tip of the contact element 301 to move not only downwards, but also sideways in a rocking and non-sliding motion.